401(k) Plan	12 Months Ended
Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
401(k) Plan	18. 401(k) Plan The Company has a defined contribution plan that covers all employees over the age of 21 who have been employed for at least 90 days. The plan is subject to the provisions of the Employee Retirement Income Security Act of 1974. In accordance with the provisions of the plan, the Company may make discretionary contribution to the account of each participant. During the years ended December 31, 2017, 2016 and 2015, the Company made contributions of $336, $248 and $181, respectively.

401(k) Plan

12 Months Ended

Dec. 31, 2017

Compensation And Retirement Disclosure [Abstract]

18. 401(k) Plan

The Company has a defined contribution plan that covers all employees over the age of 21 who have been employed for at least 90 days. The plan is subject to the provisions of the Employee Retirement Income Security Act of 1974. In accordance with the provisions of the plan, the Company may make discretionary contribution to the account of each participant. During the years ended December 31, 2017, 2016 and 2015, the Company made contributions of $336, $248 and $181, respectively.